THE AVONIAN OP THE AVON GORGE 
151 
Beak not differentiated from the flanks, and its apex not 
incurved over the area. 
Teeth well developed. 
Muscular scars arranged on the Productoid pattern, but very 
lightly impressed T 
A. row of hollow spines along the cardinal edge ; these spines 
are the bent continuations of slender tubuli which per- 
forate the shell immediately below the surface of the area. 
Brachial valve weakly concave or flat, with strong 
sockets, mesial septum and thickened cardinal process. 
Ornament: 
Longitudinal ribs which increase by forking and inter- 
calation. 
Spines practically absent, except along the cardinal edge. 
The under layer of shell exhibits very characteristic rows 
of close-set pits along every furrow ; into these pits fit 
corresponding rows of small spikes which project from the 
under-surface of the outermost shell-layer. 
Bmiesiella. 
Figures: Dav. Plate 47. 
Spineslon cardinal edge 
tGardinal 'process 
Pedide} 
Valve 
Depressions 
Daviesidla ( —Producti-Glio'netes) aff. comoides. 
Pedicle valve and^section. 
1 The weak impression of the muscular scars is the direct consequence 
of the thinness and flatness of the valves. 
